Zulip Chat Archive

Stream: maths

Topic: Asymptotic series


Yury G. Kudryashov (Oct 23 2023 at 17:08):

I'm going to formalize asymptotic series of a function along a filter, with lemmas like uniqueness and "if there exists an asymptotic series up to each finite order, then they all glue together into 1 asymptotic series". Is there any standard reference on this topic, or should I start with some definition that fits my use cases and, if needed, generalize later?

Yury G. Kudryashov (Oct 23 2023 at 17:11):

Use cases that I care about:

  • Taylor series;
  • "Dulac series" f(z)=az+b+kPk(z)eνkzf(z)=az+b+\sum_k P_k(z)e^{-\nu_k z}, where 0<ν0<ν1<0<\nu_0<\nu_1<\dots, in a domain C(1+z)zC(1+\sqrt{|\Im z|})\le \Re z (appears in Ilyashenko's proof ot the fact that an analytic vector field on the sphere with hyperbolic singular pts only can't have infinitely many limit cycles).

Michael Stoll (Oct 23 2023 at 17:22):

I think analytic number theorists also care about series involving powers of log (or even log log). E.g. like this.

Sebastien Gouezel (Oct 23 2023 at 18:07):

Eberl uses a very general notion of asymptotic series in http://cl-informatik.uibk.ac.at/users/meberl//pdfs/real_asymp.pdf

Yury G. Kudryashov (Oct 23 2023 at 18:51):

@Michael Stoll The series above is in fact in the logarithmic chart, so in the original chart it would use polynomials of logarithms multiplied by real powers.


Last updated: Dec 20 2023 at 11:08 UTC